Efficient process control is an integral part of the design and operation of a safe and productive chemical plant. It is crucial for fault tree analysis since control systems are designed to prevent process deviations. How to handle control loops is a major concern in the research of computer-aided fault tree synthesis for the chemical process industry (CPI). This paper presents a systematic methodology to produce fault tree models for control loops and protective safe guards. Two examples are provided to illustrate the basic idea. (C) 2003 Elsevier Ltd. All rights reserved.